Question: On the first 6 exams of her language class, Emily got an average score of 86. What does she need on the next exam to have an overall average of 88?
Solution: Let her score on the next exam be $x$ The sum of all of her scores is then $6 \cdot 86 + x$ The same sum must also be equal to $7 \cdot 88$ Solve: $x = 7 \cdot 88 - 6 \cdot 86 = 100$.